GRAvity wave short term Variability In the Thermosphere/Ionosphere induced by GLObalscale Waves (GRAVITIGLOW)

大气波在中层大气与热层/电离层（T/I）之间的垂直耦合对热层/电离层的能量和动量平衡起着重要作用。这些大气波包括全球尺度波（行星波、潮汐）和中尺度重力波（GWs）。模拟和观测表明，在向上传播过程中，GWs可以与全球尺度波相互作用。全球尺度波对GW的调制改变了GW动量通量的大小、破碎位置和饱和高度。这不仅会影响热带气旋的全球分布，也会影响热带气旋全球环流的波驱动。此外，通过与GWs的相互作用，全球尺度波本身也受到影响。此外，由于低海拔地区的千兆瓦滤波导致千兆瓦分布的不均匀性，在T/I区也可以激发全球尺度波。此外，背景变化（特别是全球尺度波）对GWs的选择性过滤影响了平流层突然变暖（SSWs）期间T/I的波强迫。因此，为了更详细地了解这些过程，需要同时对全球GWs和全球尺度波进行全球观测，以及对大气中层进行全球观测。在这个项目中，我们将使用不同的卫星测量，包括CHAMP、GOCE、GRACE、SWARM（在T/I）和SABER、HIRDLS（在中层大气），分析全球尺度波引起的gw的短期变率。在T/I中，除了通过CHAMP和GOCE成功推导出GW的全球分布外，我们还将采用相同的方法从SWARM、CHAMP和GRACE的质量密度、风和等离子体密度中推导出GW的分布。此外，潮汐振幅和潮汐相位将从SWARM、CHAMP、GOCE和GRACE的质量密度、风和等离子体密度中得出。将分析这些同时观测到的吉瓦和潮汐，以估计潮汐对吉瓦的调制作用。另一个重点是在每一次热带风暴事件的中心日期前后T/I中GW分布的变异性。此外，我们将研究背景变化（特别是全球尺度波）对吉瓦的调制如何影响ssw期间吉瓦的垂直耦合。对于这些SSWs，将对中层大气和T/I的观测数据进行高时间分辨率分析。射线追踪将用于研究SSWs期间中层大气中GW光谱的过滤。长期SABER数据和SWARM、CHAMP、GOCE、GRACE数据的结合提供了全面的研究案例集合。我们项目所获得的gw和潮汐观测资料，对于与一般环流模式所模拟的相应数量进行直接比较也很重要。

Vertical coupling between middle atmosphere and thermosphere/ionosphere (T/I) by atmospheric waves plays an important role in the energy and momentum balance of the T/I. These atmospheric waves include global scale waves (planetary waves (PWs), tides) and mesoscale gravity waves (GWs). It has been modeled and observed that during upward propagation, GWs can interact with global scale waves. The modulation of GWs by global scale waves alters the magnitude of GW momentum fluxes, breaking location and saturation altitudes of GWs. This will affect not only the global distribution of GWs in the T/I but also the wave driving of the global circulation in the T/I. Further, by interaction with GWs, global scale waves are themselves affected. Also, global scale waves can be excited in the T/I due to the non-uniformities of the GW distribution that resulted from GW filtering at lower altitudes. Moreover, selective filtering of GWs by background variations, in particular by global scale waves, influences the wave forcing in the T/I during sudden stratospheric warmings (SSWs). Therefore, simultaneous global observations of GWs and global scale waves in the T/I, together with global observations in the middle atmosphere, are needed to better understand these processes in more detail.In this project, we will analyze the short term variability of GWs induced by global scale waves using different satellite measurements, including CHAMP, GOCE, GRACE, SWARM (in the T/I) and SABER, HIRDLS (in the middle atmosphere). In the T/I, in addition to the global distributions of GW, which were successfully derived from CHAMP and GOCE, we will apply the same method to derive GW distributions from mass density, winds and plasma density from SWARM, CHAMP, and GRACE. Further, tidal amplitudes and tidal phases will be derived from mass density, winds, and plasma density from SWARM, CHAMP, GOCE, and GRACE. These simultaneous observations of GWs and tides will be analyzed to estimate the modulation of GWs by tides. Another focus is the variability of GW distribution in the T/I around central date of each SSW event. Further, we will investigate how the modulation of GWs by background variations, in particular by global scale waves, influences the vertical coupling by GWs during SSWs. For these SSWs, observations both in the middle atmosphere and in the T/I will be analyzed with high temporal resolution. Ray tracing will be performed to investigate filtering of GW spectrum in the middle atmosphere during SSWs. Long-term SABER data and combination of SWARM, CHAMP, GOCE, GRACE data provide a comprehensive collection of study cases. Observations of GWs and tides derived by our project are also important for direct comparison with corresponding quantities simulated by general circulation models.